Turning off a vehicle engine when the vehicle comes to a stop can improve fuel economy and reduce emissions. Ideally, the engine would be started again before a power demand is made by the driver. Some ways to anticipate the driver's power demand include when the driver presses the accelerator pedal (for vehicles with automatic transmissions) or when the driver actuates the clutch and gear shifter (for vehicles with manual transmissions). Restarting the engine before the power demand is made balances quickly responding to the driver's power demand with providing improved fuel economy and reduced emissions relative to vehicles where the engine runs continuously during operation of the vehicle.